Effect of Squat Depth and Barbell Load on Relative Muscular Effort in Squatting.

MedLine Citation:

PMID:
22797000
Owner:
NLM
Status:
Publisher

Abstract/OtherAbstract:

ABSTRACT: Resistance training is used to develop muscular strength and hypertrophy. Large muscle forces, in relation to the muscle's maximum force generating ability, are required to elicit these adaptations. Previous biomechanical analyses of multi-joint resistance exercises provide estimates of muscle force but not relative muscular effort (RME). The purpose of this investigation was to determine the relative muscular effort (RME) during squat exercise. Specifically the effects of barbell load and squat depth on hip extensor, knee extensor and ankle plantar-flexor RME were examined. Ten strength-trained women performed squats (50-90% 1 RM) in a motion analysis laboratory to determine hip extensor, knee extensor and ankle plantar-flexor net joint moment (NJM). Maximum isometric strength in relation to joint angle for these muscle groups was also determined. RME was determined as the ratio of NJM to maximum voluntary torque matched for joint angle. Barbell load and squat depth had significant interaction effects on hip extensor, knee extensor and ankle plantar-flexor RME (p<0.05). Knee extensor RME increased with greater squat depth but not barbell load, whereas the opposite was found for the ankle plantar-flexors. Both greater squat depth and barbell load increased hip extensor RME. These data suggest training for the knee extensors can be performed with low relative intensities but require a deep squat depth. Heavier barbell loads are required to train the hip extensors and ankle plantar-flexors. In designing resistance training programs with multi-joint exercises, how external factors influence RME of different muscle groups should be considered to meet training objectives.